I've got a 4" submersible pump installed and I'm trying to find the specs
for it so that I can purchase a new pressure tank.
It's a Goulds and the model number is 5ES03412. It was installed 12 years
Can anyone tell me the discharge rate or the horsepower of this guy?
That should be a 1/3hp due to the 03 but I don't know for sure. If it
were a 05 it would be a 1/2 hp (you didn't mis read it or type it
incorrectly?), a 5ES10412 (3 wire, control box in the house) is a 1 hp,
15 a 1.5 hp, 07 a 3/4 hp etc.. It's an old model and not produced today
You don't size a pressure tank based on the hp of a pump. The hp only
relates to the motor, and the motor turns the wet end, or the actual
pump if you will. The 5ES says you have a 5 gpm wet end, or pump that
uses a 1/3hp motor. Now that, the hp, is then shall we say, regulated by
the water level in the well, the depth of the pump, the pressure range
you operate the pump at, the TDH (total dynamic head) of the entire
water system on and on.
So.... turn on your water at a faucet until the pump turns on, note the
pressure, then shut off the water and note the pressure the pump shuts
off at; I.E. 30/50. Then take a 5 gallon bucket and run water in it from
the drain on your pressure tank tee and time the pump run time and
measure how much water you get in 60 seconds. Maybe 2 or more 5 gal
buckets will be needed if you have a large pressure tank. You want the
pump to run at least 60 seconds (for proper cooling of the motor). The
gpm your 'system' delivers to the pressure tank in a minute is the gpm
of the system, regardless of what hp and gpm pump you have. Size the
tank, based on the drawdown at the pressure range you use, to provide
the manufacturers' minimum run time of one minute (60 seconds). This
drawdown is the amount of water between the pump shutting off and coming
on again. Another drawdown is how far the water level in the well falls
when you pump the well for say 15-30 minutes, and you don't need t
oknow that for this project.
Caution, many GUYS mistakenly think larger is better, and that's not
true in this case or many others. Going to a very large pressure tank
(say 40 gallon or more drawdown at 30/50 psi) can cause a dry well
condition (pump sucks air), ruin the pump (overheat it), cause poor
water quality problems (open other areas of recovery water with high
whatever that you don't want in the water; like mud, iron etc.) and
possibly, the collapse of some wells.
Quality Water Associates
Gary, great post - thanks!
Would it be possible to calculate the desired drawdown by using this
(new drawdown) = (existing tank drawdown) * 60 / (# seconds to
complete current cycle)
Essentially I'd like to 'cheat' and calculate the desired tank
drawdown capacity, by just assuming pump runtime would scale linearly
with tank drawdown capacity. Could it be this easy if we felt like
playing with numbers instead?
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